What is more important, is that it is only AHCI and not NVMe.
In particular, NVMe has much lower latency, and massively greater parallelisation which greatly increases performance for virtual memory.
Both this machine and the new MacBook Pro's have soldered memory but this will be far more limiting without NVMe support, which the MacBook Pro's have.
It's not unrepairable. It's just unrepairable by unequipped amateurs, which is where iFixit sell their bits and pieces.
And those same things that make it more difficult to repair, also make it less likely to go wrong in the first place.
Again, not in iFixit's commercial interest to encourage.
"We're so close to the Touch Bar we can almost, well, touch it."
except that you broke it in step 13, so mind you don't cut yourself.
"These speakers likely blast their impressive sound through the side air vents."
Eyes are useful, but for some things Ears can be a better tool?
"...fingerprint reader, the tech has been around since at least 2004...."
But Apple's works. Not just as a demo, but on an everyday basis.
Apple control so much of what they use that it gives them potential to go a long way outside the box.
Given that they totally control the SSD controller, then there are things that they could do to greatly improve paging performance to fast SSD. And those things could well involve wanting the widest memory path that they can get.
Definitely based on.......?
"Today's million-dollar question: Is this a scaled-up version of the 13-inch "Escape Edition," or a scaled-down version of the 15-inch Touch Bar unit? Here's what the tech specs tell us:"
So we'll need the teardown of the 15" to be sure.
Strange then that Microsoft has been remodelling their whole business to be more like Apple, e.g. producing complete systems that they control from end to end, and largely failing, e.g. effectively writing off their Nokia acquisition.
"It is absurd. The M.2 standard is just fine for everyone."
It clearly isn't fine for everyone, or Apple would be using it.
Why is a hard call, but given Apple's use of a custom SSD controller, they could be doing things that other interface architectures simply don't support.
Owning the whole chain, end to end, opens up all sorts of possibilities, for example for speeding up virtual memory paging related I/O. If that were the case, then I doubt that Apple would tell you anything other than that it's much faster in some situations, as indeed they did.